This invention relates to a chair, specifically to an office chair, comprising a support panel for a seat element and a substantially vertical back support element. The present office chair allows the user to influence and adjust his or her seating dynamic to varying degrees.
In contrast to a rigid chair, where there is no provision for changing the relative positions of seat to backrest, the office chair has provision for adjusting those relative positions according to the requirements of the user.
The mechanisms provided in an office chair serve to encourage the user into a dynamic sitting behavior. This entails changing his or her position regularly, thus avoiding muscular discomforts such as cramp or fatigue and, thus, allowing the user to sit for longer periods without experiencing the normal problems associated with prolonged sitting, or, at least, substantially reducing those effects.
Well known mechanisms for adjusting seating positions on office chairs allow for the tilting of the backrest, the seat panel, or even a combination of both.
An example of such a chair mechanism is know from EP2725943 A1 (L & P Property Mgt) which discloses an office chair which accommodates some of the user's movements and whose seat panel tilts and moves backwards when the user leans backwards thus tilting the backrest.
To improve this situation a side-to-side/left-to-right motion can be added which promotes movement even further.
More recent improvements allow for the sideways rocking or “twisting” of the seat and chair. Such an arrangement is known from the German “Offenlegungsschrift” DE102014006058 (Grupo Forma) which discloses an office chair wherein the seat panel and the backrest can twist sideways thus allowing the user to rock sideways.
However, the Groupo Forma disclosure involves a rigid connection between the seat panel and the backrest such that the seat and the backrest have to move together. Such an arrangement has been shown not to be favored by many users.
A good office chair seating solution benefits the chair users by providing motion. This ensures that the chair users are not static for long periods of time as this is bad for the chair users' health.
One instance of where this movement is limited is for example if the chair user movement is limited to forwards & backwards then they drop something & suddenly reach for it. After being static for a long period sudden movement can lead to back injury.
The present invention discloses an office chair which alleviates the above problems and disadvantages.
An independent seat & back twist allows for user preference. The front connection is a ball joint located in the center plane of the seat. This ball joint is formed from two half spheres forming a complementary shaped housing enclosing the ball.
The upper half of the housing is fixed directly to the lower panel of the chair seat panel the lower part is assembled by means of bolt which reaches through the ball of the joint. This arrangement essentially creates a 360 degree pivot around the centre point of the ball joint.
The ball is mounted on the top surface of the seat element and the housing surrounding the ball is mounted under the chair seating panel, thus allowing the former to lean sideways when the user leans sideways.
The rear of the seat is essentially floating on two compression springs spaced evenly away from the central plane (these could be any spring type, rubber, leaf spring etc.). These compression springs may rest in spring pockets lodged in the seat element into which pockets the compression springs may recede when coil springs are used.
The resulting motion is best described as a rolling motion where the tilting motion is strongest at the rear of the chair seating panel and reduces in amplitude the nearer it gets to the front of that panel. A useful locking option may be to include a means for the user to lock the twisting motion, hence precluding any sideways twisting of the chair seating panel when it is not wanted.
Since it is preferable to have chair controls at the front of the seat, for easy manipulation by the user, such a locking option should be operable at the front or the front side of the chair seating panel. To guard any fingers probing in the area of the ball joint, the top panel of the seat element is turned downwards to effectively shield the moving parts of the front joint.
This locking option may be realized by putting a sliding block either side of the ball joint which sliding blocks can be moved toward the center of the seat panel or away from it, thus either increasing or reducing the effective space between the underside of the chair seating panel and the seat element.
At the rear of the seat, as it is essentially floating, two items may be added: guides to align the seat left to right. These may be profiled to shape the twist to the desired shape, i.e. conical surfaces may be added, if the twist were desired to be exactly conical.
Tilt limiters either side of the central point of the seat element are required to stop the seat from flipping over when leaning to the side. These tilt limiters may vary in form, they may be screws/bolts, wires or even integrated hook features, the latter of which are the preferred realization or embodiment. Straps could also be used at the front of the seat if required for strength purposes.